1. Field of the Invention
The present invention is related to flexible saws, and in particular is related to an improved saw of this type which is constructed of a plurality of pivotally connected blade links. Still more particularly, the present invention is related to such a saw having overlapping tooth positioning that facilitates sawing, a turn-link connected at one end that assures the teeth of the saw face the wood to be sawed, and a loose riveting that provides efficient operation of the saw.
2. Description of the Prior Art
There are many occasions when wood, particularly tree limbs, must be cut. In the case of cutting tree limbs, it can be both difficult and dangerous to perform the cut, especially in those situations where the limb is located high enough to be unreachable from the ground. There are also situations where someone must cut firewood when on a camping trip, picnic or other outing, and the appropriate saw that would do the job properly is simply too awkward and heavy to pack and carry. Accordingly, what is needed is a compact, lightweight saw which effectively cuts wood of all types and is safe and easy to use in all situations.
In the prior art there are a variety of saws that have been developed to cut limbs. There are two basic classes of saws: those which are powered and those which are operated by hand.
Of the first class of saws, the chain saw has become a familiar tool for the cutting of limbs. But, this kind of saw is heavy, very awkward to carry, and extremely dangerous, especially when cutting limbs located far off the ground. Of the second class of saws, there are several examples.
One kind of saw of the second class is that which enables the user to reach high level limbs via the use of a saw connected with an elongate handle. In this kind of saw, the saw blade reciprocates with respect to the limb by a mechanical linkage system. This kind of saw is represented by U.S. Pat. No. 605,368 to Wrublik, dated Jun. 7, 1898 and by U.S. Pat. No. 3,181,239 to Skok, dated May 4, 1965.
Another kind of saw of the second class is that which has a flexible blade which enables the blade to encircle the limb to be cut. Flexibility of the blade may be provided by either a long twisted blade or a segmented, pivotally interconnected blade. Examples of the twisted blade approach are U.S. Pat. No. 2,749,949 to De La Tramerye, dated Jun. 12, 1956 and U.S. Pat. No. 2,988,118 also to De La Tramerye. A variation thereof is exemplified by U.S. Pat. No. 1,616,880 to Swanstrom, dated Feb. 8, 1927, where disclosed is a resilient wire that is wound with two threads that form teeth, and the resilient wire is reciprocated with respect to a handle connected with each end of the wire. The segmented, pivotally interconnected blade system has proven most effective and efficient, and will now be discussed in particular detail below.
Early examples of the segmented, pivotally interconnected saw blades are U.S. Pat. No. 3,192,973 to O'Link, dated Jul. 6, 1965, which discloses a flexible blade constructed from a number of interconnected links, each link being provided with teeth members for cutting; and U.S. Pat. No. 3,999,294 to Shoben, dated Dec. 28, 1976, which discloses a flexible blade constructed of a number of blade segments interconnected pivotally with links, the flexible blade being guided around the limb by a curved housing.
While the foregoing examples of flexible saw blades are of interest, none truly is a truly practical saw. Closer to the goal is the segmented, pivotally interconnected saw blade disclosed in U.S. Pat. No. 3,747,652 to Meadows, dated Jul. 24, 1973. Meadows' blade is constructed of a plurality of serially arranged blade segments, overlapping only at the edges and being connected thereat by grommets to provide pivotal function between the blade segments. Ropes connect at the ends of the blade to permit the user to execute reciprocal movement of the blade segments against the limb to be cut.
The saw of Meadows suffers from a number of very significant disadvantages. Among these are difficulty to ensure the cutting teeth engage the limb when the blade is thrown over it and reciprocal movement is engaged, two-way flexibility of the blade making it very difficult to know whether during reciprocation the teeth or the opposite side of the blade segment therefrom is actually engaging the limb, poor pivotability due to the grommets being either too loose or too tight, and inefficient cutting due to the teeth not being positioned for optimal cutting. Also, the blade tends to be excessively transversely bendable, making use somewhat unweildy.
Applicant has sold for over one year a prior art segmented, pivotally interconnected saw blade, shown in FIGS. 14 and 15, which solves some of these problems. In particular, Applicant's prior art flexible saw blade 10 is constructed of a plurality of cutting links 20, arranged in two side-by-side rows. The cutting links 20 are connected together by hollow rivets 22. Each cutting link has two integral teeth 24, and each tooth bends away from the teeth of the adjacent cutting link, as shown best in FIG. 15 in order to provide a kerf wider that the width of the cutting links and the associated hollow rivets. The ends of the cutting links have a curved portion 26 that permits pivoting at the rivets in one direction, and a flat portion 28 which prohibits pivoting in the opposite direction. The hollow rivet 22 has a V-shaped exterior cross-section 30 which mates with a reciprocably shaped hole 32 in adjacent cutting links, thereby retaining the adjacent cutting links in pivotal communication with each other. Because two side-by-side rows of cutting links are used, transverse bending of the blade is quite minimal, thereby making use predictable and easy. Also, because pivotability is in only one direction, the direction necessary for the teeth to engage the limb, the user always knows that the teeth are doing their job as he/she reciprocates the blade relative to the limb.
Now, while Applicant's prior art saw blade is an improvement over all prior devices, including that of Meadows, there yet remains several significant disadvantages that must be solved. For one, there remains the problem of how to assure that just the right degree of rivet pressure will act on adjacent cutting links so that pivoting is easy but not too loose. For another, by pointing the teeth from one another to ensure sufficient kerf width to allow the saw to pass through the limb as it cuts, inefficient cutting occurs due to uncut wood forming a ridge between the teeth of adjacent cutting links after each reciprocation of the blade. Lastly, while the blade may be able to pivot in only one direction, nonetheless, it would be most beneficial for the blade to be caused to automatically right itself with respect to the limb surface upon being passed over the limb and before actual cutting begins.